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Discussion Starter #1
Hi All!

I was planning on rebuilding my merc 25 2 smoker this next week. (Low compression and was dying after coming off plane and difficult starting). Threw the spare motor on the boat and got to work.

Turns out I have scoring on the cylinder walls and some on the pistons. To add to it the block has already seen a rebuild job. The pistons measured at .030" (2.583") over the stock manufacture size of 2.558". Is there anything to do now? I will be seeing the machinist on Monday to see what he can do/suggest.

It does have the Mercosil Block. The repair book doesn't list anything over .030 but I see there are pistons for .040" over.

Would love some insight!
 

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Discussion Starter #4
Let's hope my measurement device is inaccurate! It has been pretty beat up.
 

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Those things use an aluminum with a very high silica content that allows them to run without sleeves. I've never heard of someone re sleeving one?
 

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Discussion Starter #9
I see an outboard machinist here in town. Supposedly ~30 years of experience. Will post up results tomorrow.

I am not opposed to any mods. Reliability is still #1. Thankfully no downtime from fishing from a motor that is torn apart!
 

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The scoring may clean up with some honing. The major culprit is a cylinder usually gets ovaled, or egg shaped. It's not noticeable with the eye, but you will see it when you mic the cylinders. I'm not very familiar with marine engines, so the actual alloy of the block may disallow sleeves. Definitely see a marine specialist.
 

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I've had nikosil mx bike cylinders sleeved. not all can be done cause over boring for the sleeve can conflict with the power valves but not an issue on an old merc.
 

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Discussion Starter #14
I think the machinist is flaking... Any one know of a machinist near Jax?
 

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Discussion Starter #18
No not true, a machine shop as well n sell mercury parts too....
Sign into scream n fly many people knowledgeable mercury people. Chris Carson does mercury motors...
Yep I reached out to the guys over there and they are split. One guy did say that there is a .040" over piston for my engine! So there is hope!

I just put the new axle on the trailer. I think I can swing by the machine shop tomorrow. The shop was supposedly closed for the last couple of days due to meetings...
 

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Discussion Starter #19
Alright here the story. The machinist is old school and has been refinishing blocks for about 30 years. REAL DEAL!

The block I have... Cylinder #1 is near perfect only out .0005 in one spot, cylinder #2 needs a sleeve. It would be about $400 to throw the sleeve in there or more.

Can you run different sized bores in the same block? I may just try to find another powerhead that hasn't had any work done on it and rebuild that one.

Very random thought, While talking to the machinist a gentleman walked in, turns out to be an descendant 8th generation of the Davey Crockett.
 
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